A number of companies, including one chaired by former prime minister Bob Hawke, are negotiating to capture excess water from swollen rivers on the state's high-rainfall west coast.

(Tasmanian state) Water Minister David Llewellyn told The Weekend Australian he now believed the idea stacked up economically -- and could be used to benefit Tasmanians as well as mainland consumers.

Mr Llewellyn said a proposal from Solar Sailor, a NSW company chaired by Mr Hawke, to export 50 billion litres of water a year from Tasmania, was just one of a number before the Government.

Mr Llewellyn said Tasmania's fresh water supplies were equivalent to two Murray-Darling systems. The state has a population of about 485,000, or 2.3 per cent of Australia's total, yet it has 12 per cent of the nation's water.

Mr Llewellyn said revenue from the sale of water otherwise flowing from rivers into the sea could be invested in dams and irrigation infrastructure in the state's dry north and east.

Tasmania's west coast, home to wild mountains and swollen rivers, often complains of an excess of rain while parts of the state's east and north are in drought.

Although only one of a number of proposals, Solar Sailor is understood also to be in discussion with several mainland states as potential customers for Tasmanian water.

The company's chief executive, Robert Dane, who has held talks with Tasmania's Department of Primary Industries and Water, has flagged using several supertankers to ferry water to centres along the eastern seaboard, including Sydney, Melbourne and Queensland.

Even if the exported water was sold in bulk for a few cents a litre to East Coast cities, exporting 50 billion litres of it a year is going to make some people extremely wealthy.

Maybe the supertankers should load up on melting ice from the Antarctic. Not only will the resulting water be cleaner, wouldn't scooping up all that melting ice and shipping it to Sydney help slow the supposed sea level rises that are likely to result from global warming?